This proposal aims to study in detail the mechanism involved in the biosynthesis processing and secretion of human chorionic gonadotropin in chorionic villi from first term placenta. For this we plan to study the quantity and the characteristics of secretion of hCG during placental development. We propose to investigate the intracellular location of the assembly of the primary amino acid sequence as well as the site of glycosylation of hCG. The glycolytic enzymes involved also will be investigated and the possible involvement of the endoplasmic reticulum and the Golgi apparatus will be followed. We propose to study the mode of hCG synthesis in a cell-free system in order to find out whether both the alpha and beta subunits are synthesized as large precursors and then processed. For this we intend to use a reticulocyte cell-free system as well as a wheat germ cell-free system and to identify the labeled protein synthesized in a cell-free system by radioautography after trypsin digestion and fingerprinting in the presence of known subunit carrier protein. We propose to obtain this specific mRNA for each of the individual subunits by precipitating specific polysomes carrying the nascent peptides for alpha or beta hCG subunits. Preliminary results have shown that antibody against hCG subunit can be immunoabsorbed to nascent chain. Therefore, the specific polysomes carrying mRNA for alpha and beta subunits could be precipitated and isolated by employing double antibody immunoprecipitation.